1. Field of the Invention
This invention relates generally to the storage of granular material such as animal feed, and more particularly, to a method and apparatus for maintaining uniform mass flow of granular material out of a container.
2. Description of the Related Art
In various industries such as those involving agriculture and manufacturing, it is often necessary to store relatively large amounts of granular material. In agriculture, for example, it is often necessary to store substantial quantities of feed for animal husbandry operations. When used in such industries, the granular material is often initially loaded into an opening located at the top of a container which is used for temporary storage of the granular material. The granular material is then later removed from the container immediately prior to use through an opening located at the bottom of a funnel-shaped portion of the container.
Depending on the nature of the granular material that is being stored, there are often difficulties associated with using such containers. For example, granular material may often include a number of different constituents which tend to separate when loaded into a container. For example, feed for chickens generally includes a fine constituent which tends to be located in the center of the container while the container is being loaded, as well as a coarse constituent which tends to be located near the walls of the container when the container is being loaded. Because the constituents separate in this manner when they are loaded into the container, it is not generally possible to remove the granular material from the container with the same proportion of constituents as was present when the granular material was loaded into the container. In animal husbandry operations, this separation of the constituents of the feed may typically cause lower productivity. Accordingly, there is a need for substantially uniformly distributing the constituents of the granular material within the container.
In addition, granular material which is loaded into a container may not be evenly distributed within the container in that there may be a large variation in the height of the granular material around the uppermost region of the container. Not only does this reduce the effective storage capacity of the container, but the areas within the container which are not filled with granular material allow moisture to accumulate which tends to cause the granular material to degrade to various processes such as by the formation of mold. Accordingly, there is also a need for substantially evenly distributing the granular material within the container.
Moreover, granular material which is stored in the container may tend to absorb moisture at the lower funnel-shaped portion of the container during a rainfall. This generally occurs because the funnel-shaped portion of the container converges at an outlet portion and the flow of rain is thus routed directly to the outlet portion along the sides of the container. Again, this condition degrades the granular material, as well as clogs up the outlet portion. Accordingly, there is an additional need to divert the flow of rain away from the lower funnel-shaped portion of the container to maintain the lower funnel-shaped portion of the container in a substantially dry condition during a rainfall.
Still further, as the granular material is removed from the container at the lower outlet portion using a conventional boot and auger assembly, the granular material tends to unload unevenly and have a non-uniform mass flow. In worst case conditions, a side unloading condition may occur within the container, where the granular material is generally flowing out of the container more along one side of the container causing the slower flowing granular material to concentrate along a higher wall. This uneven distribution of granular material within the container may result in collar warpage or damage along the lower outlet portion and, in extreme circumstances, panels along the lower funnel shaped portion may split and give way under the uneven loading of the granular material. Furthermore, this type of unloading may also cause what is known as "bridging" of the granular material within the container where pockets or portions of the granular material are removed leaving a subsequent bridge of granular material which, over time, may fall or "feed crash" within the container, further causing potential structural problems to the container.
Various methods and devices have been developed in an effort to distribute granular material entering a container. As shown in FIG. 1, one particular type of device, generally known as a spreader, has been used for distributing grain within a grain bin. Such a spreader is typically located at the upper region of the grain bin and includes a slide which is rotated by a motor. As the granular material is delivered to the slide, the granular material flowing along the slide is distributed at various locations within the grain bin.
While such a spreader has been used generally successfully in distributing grain within a grain bin, there are nevertheless several disadvantages associated with such a spreader. For example, the use of a motor to rotate the slide necessarily increases the cost of the spreader. In addition, the use of a motor to rotate the slide tends to make the operation of the spreader susceptible to motor failure and therefore less reliable. Furthermore, it is not generally easy to determine whether or not the motor driving the slide has indeed failed thereby causing the slide not to rotate because the slide and the motor are generally hidden from view. Finally, such a spreader has generally only been associated with the distribution of grains in grain bins and has not generally been used to distribute animal feed in feed bins.